nexus sim: more irq fallout

There's 1 fewer assigned irq. Not sure why things worked w/o this.

Change-Id: I4a1d123b83fe3d6bc553d7dd4eeda439e48f7d86

platforms/nexus_smc.repl

diff --git a/platforms/nexus_smc.repl b/platforms/nexus_smc.repl
index 4ff315e..65fd3d5 100644
--- a/platforms/nexus_smc.repl
+++ b/platforms/nexus_smc.repl
@@ -17,7 +17,7 @@
 smc_plic:
     0 -> cpu1@9
     1 -> cpu1@11
-    numberOfSources: 43
+    numberOfSources: 42
 
 uart5: @ sysbus 0x54000000